Centrifugal separator

ABSTRACT

A centrifugal separator for the three-phase removal of clear liquid, semiclear liquid and solids from slurry. A high-speed carrier which rotates about a vertical axis carries two or more eccentrically disposed slurry-receiving baskets which are individually rotatable at low speed about their respective vertical axes, the carrier and baskets presenting a balanced arrangement. A spiderlike manifold which has radial distribution channels and rotates with the carrier deposits slurry in the central region of each basket where it is flung outwards under the influence of the centrifugal force that is exerted by the carrier, and in so moving it encounters one at a time the concave sides of a series of nested involute imperforate spiral carriermounted vanes at such times as these vanes assume outer ecliptic positions with respect to the central axis of the carrier and the orbiting axes of the baskets. The vanes function as individual centrifuge units and in the manner of pouring cups which restrain the slurry against outward movement long enough to effect radial settling of the solids toward the concave sides of the vanes. During such radial settling, the less dense material or clear liquid is drawn off through the bottom walls of the baskets at inner radial regions, the denser or semiclear liquid containing solids that have not yet achieved separation is similarly drawn off at outer radial regions, while the remaining solids from which most of the liquid has been removed, are discharged over the receding or trailing edges of the vanes where they are flung radially from the baskets as well as from the carrier.

United States Patent [72] Inventor William H. Peck Tulsa, Okla. [211 App]. No. 57,533

[22] Filed [45 Patented [7 3 Assignee July 23, 1970 Dec. 14, 1971 Centrifugal Separators, inc. Tulsa, Okla.

[54} CENTRIFUGAL SEPARATOR 24 Claims, 9 Drawing Figs.

[52] U.S. CL... 210/325 [5i] lnt.Cl..... B01d33/00 [50] Field of Search... 210/325,

Primary Examiner-Reuben Friedman Attorney-Norman H. Gerlach ABSTRACT: A centrifugal separator for the three-phase removal of clear liquid, semiclear liquid and solids from slurry.

"rnnnnuu A high-speed carrier which rotates about a vertical axis carries two or more eccentrically disposed slurry-receiving baskets which are individually rotatable at low speed about their respective vertical axes, the carrier and baskets presenting a balanced arrangement. A spiderlike manifold which has radial distribution channels and rotates with the carrier deposits slurry in the central region of each basket where it is flung outwards under the influence of the centrifugal force that is exerted by the carrier, and in so moving it encounters one at a time the concave sides of a series of nested involute imperforate spiral carrier-mounted vanes at such times as these vanes assume outer ecliptic positions with respect to the central axis of the carrier and the orbiting axes ofthe baskets. The vanes function as individual centrifuge units and in the manner of pouring cups which restrain the slurry against outward movement long enough to effect radial settling of the solids toward the concave sides of the vanes. During such radial settling, the less dense material or clear liquid is drawn off through the bottom walls of the baskets at inner radial regions, the denser or semiclear liquid containing solids that have not yet achieved separation is similarly drawn off at outer radial regions, while the remaining solids from which most of the liquid has been removed, are discharged over the receding or trailing edges of the vanes where they are flung radially from the baskets as well as from the carrier.

Pmmmdi Dem 1% I'M 4 Sheets-Sheet 4 CENTRHWGAL SlElPAlltA'TUllll The present invention relates generally to a centrifugal separator and has particular reference to a novel separator of the type which is employed for separating solids from a liquid (slurry) as, for example, in connection with the drying of sand, coal and various other granular materials or in the pelletizing of minerals such as iron ore. More specifically, the invention is concerned with a centrifugal separator of the orbiting basket type such as is exemplified in US. Pat. No. 3,402,821, granted on Sept. 24, 1968 and entitled CENTRll-UGAL SEPARA- TOR," and the present separator is designed as an improvement over such patented separator.

The centrifugal separator of the aforementioned patent consists essentially ofa high-speed, rotatable, power-driven carrier on which there are mounted a plurality of independently rotatable slurry-receiving baskets which are circumferentially spaced at eccentric positions on the carrier so that upon rotation of the carrier, they orbit about the axis of the carrier. A rotary feed hopper and slurry distribution assembly having radially extending distribution channels deposits a portion of the slurry to be processed in the central region of each basket during the orbiting and rotational movements of the latter and each basket is provided with a series of curved filter screens, the concave sides of which face generally toward the axis of rotation of the basket so that upon rotation of the basket the screens perform alternate filtering and self-cleaning operations. When a particular screen assumes an outer ecliptic position, the concave side of the screen is presented counter to the direction of the centrifugal forces which are initiated by the high-speed rotation of the carrier. When the screen assumes an inner ecliptic position counter to the direction of centrifugal force and toward the oncoming slurry, such solid particles which ordinarily would tend to clog the screen during a subsequent pass of the slurry therethrough are flung free of the screen by centrifugal force. in this manner, the tendency for solid particle buildup (cake formation) on the screen is obviated. in various intermediate positions of any particular filter screen when the latter is moving between its outer and its inner ecliptic positions, the screen assumes a generally radial position with respect to the axis of rotation of the carrier so that the solid particles from which moisture has been removed by the filter action of the screen are caused to slide along the screen and become discharged radially outwardly in all directions and are thus removed from the apparatus. The liquid which passes through the screens is trapped by a collector wall behind, i.e., radially outwardly of, each screen and is discharged by gravity downwardly through discharge openings which are associated with such walls.

It has been found that while a centrifugal separator such has been described above is entirely satisfactory for certain slurries, when it is applied to slurries having solids smaller than 200 mesh, an excess amount of the -200 material passes through the screens and is discharged with the effluent, and in all cases, the effluent contains the material and, therefore, is not clear liquid.

The present invention is designed to overcome the abovenoted limitations that are attendant upon the construction and use of the aforementioned orbiting basket-type separator of US. Pat. No. 3,402,821, and toward this end, the invention contemplates the provision of a centrifugal separator wherein the orbiting baskets are completely devoid of perforate screens, yet in which the baskets function to remove a major portion of the liquid content of the slurry undergoing processing in an efficient manner, regardless of the nature of the slurry. According to the invention, particles of 200 mesh and smaller, irrespective of density, that are in suspension in a liquid are discharged as a compacted solid, and at the same time, clear liquid from which substantially all traces of particles have been removed is separately discharged. Additionally, a third separate discharge is provided for semiclear liquid, i.e., liquid containing some particles which do not have time to completely settle by the time the compacted solid is ready for discharge. Additionally, a third separate discharge is provided for semiclear liquid, i.e., liquid particles which do not have time to completely settle by the time the compacted solid is ready for discharge. This semiclear liquid may he recirculated in the separator on a continuous basis so that the end products of any given run of slurry are the clear liquid and the solids.

in carrying out the invention, the rotating baskets of the improved centrifugal separator are provided with imperforate involute vanes in place of the former perforate vanes or screens, the vanes of the baskets being disposed in nested relationship and in such a manner that during rotation of the baskets they alternately assume outer ecliptic positions wherein their concave sides are presented counter to the direction of the centrifugal forces acting on the slurry, and inner ecliptic positions wherein they are completely withdrawn from the radial path of movement of the slurry. in its outer ecliptic position, each solid wall vane of a basket thus functions for a brief interval of time in the manner of an individual conventional solid wall centrifuge and receives the slurry thereagainst, blocking its radial progress and effecting rapid settling of the solids on the concave side thereof under the steadily increasing centrifugal force that is applied thereto. This results in a radial gradation of the solids from the central point of entry thereof into a basket to the surface of each vane of the basket, the clear liquid remaining in a region remote from the vane and the solids becoming compacted against the vane in the form of a cake. Small discharge openings in such remote regions of the baskets drain the clear liquid from the baskets. As each basket continues to rotate and each vane gradually reverses its direction with respect to the radial path of movement of the slurry with respect to the carrier, i.e., as the vane gradually turns its other side toward the axis of the carrier, portions of the vane move progressively into generally radial positions so that the prevailing centrifugal force causes the aforementioned unsettled solids and remaining liquid, i.e., the semiclear liquid, to move along the vane toward a discharge opening, near the outer edge of the vane establlishes a trap for conducting this semiclear liquid to said discharge opening. Such change of direction of the vane also gradually decreases the compacting force of the cake" against the concave side of the vane until this force becomes nonexistent and centrifugal force begins to act on the cake in the opposite direction, thus stripping the cake from the concave side of the vane and allowing it to tumble into the normal radial gravitational field and thus be ejected from the edge of the basket platform.

From the above brief descriptions of the separator shown and described in US. Pat. No. 3,402,821 and the separator of the present patent application, it will be apparent that in both separators centrifugal force is employed to effect liquid-solid separation. However, in the present separator the centrifugal force is applied in a manner which is entirely different from the manner in which it is applied in the patented separator. This fact will readily become apparent as the nature of the invention is better understood but for the present it is deemed sufficient to point out that in the patented separator centrifugal force is applied to the liquid to move in the direction of such force, i.e., radially outwards of the carrier, while restraining the solids from such movement. In the separator of the present invention, both the liquid and the solids are restrained by the presence of the imperforate vanes, and since the liquid is incompressible and is confined by the solid bowl effect of the vanes, the centrifugal force acts on the particles that are in suspension. These particles are free to move in the direction of centrifugal force in varying degrees as determined by their size, mass, and the viscosity of the liquid so that they may pile up and compact against the vanes. Then, after such compacting of the solids and as the vanes change their direction, the compacted solids are discharged at one region while they are still subject to full centrifugal force, while the clear liquid constituent of the slurry and the semiclear liquid constituent are drawn off at separate locations. Such, in essence, constitutes the principal feature and object of the present invention.

Another and important feature of the invention resides in the provision of a novel means for periodically and automatically flushing any solid accumulations which may tend to collect in the vicinity of the discharge openings for the semisolids in order to insure their proper discharge. A still further feature of the invention consists of a novel means for supplying a lubricant to certain bearing assemblies which are employed in connection with the rotating baskets. These and other novel features of the invention, not at this time enumerated, sill become readily apparent as the nature of the invention is better understood from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by the claims at the conclusion hereof.

In the accompanying four sheets of drawings, one exemplary form of the invention is shown. In these drawings:

FIG. 1 is a vertical sectional view taken substantially centrally and vertically through a centrifugal separator embodying the principles of the present invention;

FIG. 2 is a fragmentary horizontal sectional view taken substantially on the line 2-2 of FIG. 1, portions of the separator casing being broken away in order more clearly to reveal the nature of the invention;

FIG. 2a is a fragmentary side elevational view illustrating the details of certain supporting rollers employed in connection with the invention;

FIG. 3 is an enlarged horizontal sectional view taken substantially on the line 33 of FIG. 1, certain parts being broken away in the interests of clarity;

FIG. 4 is a side elevational'view of the which is shown in FIG. 3;

FIG. 5 is a fragmentary enlarged perspective view resulting from a radial sectional taken substantially on the line 55 of FIG. 3 and in the direction indicated by the arrows;

FIG. 6 is a fragmentary enlarged perspective view resulting from a radial section taken substantially on the line 66 of FIG. 3 and in the direction indicated by the arrows;

FIG. 7 is an enlarged fragmentary detail view of a portion of the structure of FIG. 1 and illustrating certain water and oil distribution facilities which are employed in connection with the invention; and

FIG. 8 is a plan view, entirely schematic in its representation, illustrating a belt drive mechanism which is employed in connection with the invention, and also illustrating the orbital and rotational characteristics of certain centrifuge baskets which are employed in connection with the invention.

Referring now to the drawings in detail and in particular to FIG. 8 wherein a schematic view or layout of the principal component parts of the present centrifugal separator are portrayed, and considering this view in conjunction with FIGS. 1 and 2, the invention is embodied in a centrifugal separator 10 including a carrier 12 which is in the form of a circular deck plate and is continuously rotatable in a horizontal plane about a vertically extending main drive shaft 14. Rotatably and eccentrically mounted on the deck-plate type carrier is an annular series of four slurry-receiving separator baskets I6 which are mounted on vertical drive hubs l8 and are equally spaced in a circumferential direction of the carrier so that they assume positions 90 apart. Although four such separator baskets are illustrated in the drawings hereof for exemplary purposes, it will be understood that a greater or lesser number of such baskets may be employed if desired, but in any instance, equal spacing thereof will be maintained for proper balance of the separator as a whole.

The various baskets 16 are thus capable of orbital revolution about the vertical axis of the carrier 12 and, additionally, are capable of individual rotation about the axes of their respective hubs I8, rotation of the carrier taking place in a counterclockwise direction as viewed in FIG. 8 at a relatively high speed on the order of 1,200 rpm. and rotation of the baskets 16 also taking place in a counterclockwise direction but at a reduced speed on the order of 6 r.p.m., as will be described in detail presently.

particular structure A rotatable feed hopper and slurry distribution assembly 22 (see FIG. 1) deposits slurry continuously onto the central regions of the baskets I6, i.e., on the hubs l8, and separation of the slurry constituents takes place in the orbiting and rotating baskets in three stages, thus dividing and discharging such constituents in the form of l) substantially clear liquid; (2) semiclear liquid; and (3) solids, these components being conducted separately from the separator as described hereafter.

To effect such separation, each basket 16 is equipped with a series of imperforate, involute, spiral, slurry-restraining vanes 24 which function as dams and are arranged in circumferentially spaced, intertwined, nested, circumferentially and radially overlapping relationship with respect to one another. These vanes project vertically from the plane of a disclike platform 26 forming a part of the basket 16, are continuous and imperforate, have their inner vertical leading edges close to the center of the platform 26, and have their outer vertical trailing edges positioned in close proximity to theperiphery of the platform.

From the above description, it will be apparent that because the various rotary baskets 16 travel or orbit bodily as individual units about the central vertical axis of the carrier 12, there will be tendency for the slurry which is deposited at the center of each basket to be flung radially outwardly in all directions from the axis of the carrier as indicated by the radial broken line arrows C in FIG. 8. Since the rotary baskets 16 themselves rotate about their respective central axes at a relatively low speed, a certain amount of centrifugal force ordinarily would be exerted upon the slurry which is deposited on the central hubs 18 0f suchbaskets. However, this small amount of centrifugal force is completely overshadowed by the high centrifugal force which is exerted on the slurry as the result of rotation of the large central carrier 12 so that it has no appreciable effect on the slurry which continues to move radially of the carrier in a direction leading to the four points of tangency between the small peripheries of the baskets and the large periphery of the deck plate type carrier. However, the various spiral vanes 24, due to rotation of the baskets, move into and out of the radial paths of movement of the slurry which is travelling across the surfaces of the baskets, and in so moving, they cause discharge of the slurry from the baskets in three ranges of solids-density. The first range of solids-density includes substantially clear liquid which flows downwardly through the basket platforms 28 through series of small holes 30 near the convex sides of the vanes 24. The remaining liquid content of the slurry is restrained by the concave sides of the vanes 24, and since the liquid is incompressible, the particles which are in suspension are subject to radial displacement under the influence of centrifugal force so that they move against the vanes and become compacted thereagainst in the form of solid cakes which adhere to the vanes. A small amount of such particles which do not have time in which to settle remains in suspension and establishes a region of semiclear liquid which slides along the vanes and becomes trapped in hooklike reentrant end portions 32 at the outer ends of the vanes and passes from the basket through discharge holes 34 which are disposed within the confines of the hooklike portions 32, thus leaving the substantially dry solids adhering to the vanes. As the baskets continue to rotate about their respective axes, the positions of the vanes 24 with respect to the radial gravitational field progressively become reversed with the net result that the compacting force of the solids against the vanes gradually diminishes while the centrifugal force acting on these solids gradually undergoes a direction change with respect to the individual vanes until a point is reached where the former compacting force exerted on the solids now becomes a loosening force tending to dislodge the dryer solids from the vanes so that they are flung radially outwardly over the peripheries of the disclike platforms 26. In the case of each basket, the holes 30 thus establish a first region of liquid discharge; the small holes 34 establish a second region of semiclear liquid discharge; and the periphery of the basket platform establishes a third region of solids discharge.

The forgoing description sets forth the basic centrifugal principles which are involved in connection with the threestage densityhseparation of the slurry by thevarious baskets without reference to collection of the separated particles and their discharge from the separator as a whole. The manner in which the carrier is rotated; the basket drive train; the split feed of slurry to the central regions of the orbiting and rotating baskets; the forced feed lubrication of certain of the bearings which are employed in connection with the separator; an auxiliary power train in the form of a belt drive for a solids impact wall which is employed in connection with the separator; and numerous other features which are foreign to the basic centrifugal principles outlined above will subsequently be set forth in detail.

To summarize the basic principle of operation, it may be considered that in connection with each basket 16, each of the vanes 2 functions as a small-capacity individual solid wall separator unit which operates a a centrifuge in that it presents a concave restraining wall which functions for a short period of time to restrain a body of slurry against outward radial movement. During the short time that it so functions, the associated series of small discharge holes remote from the concave restraining wall passes clear liquid from the body of slurry acting against the wall, while a hole 354 near the outer edge of the wall, i.e., more remote from the centrifugal center, passes additional liquid, together with such small amount of solids as remain in suspension from the slurry. The liquid is thus nearly exhausted form the body of slurry so that only compacted solids remain adhered to the concave surface of each imperforate vane 24. Then as aforementioned restraining wall (vane) moves from an outer ecliptic position with with respect to the axes of the carrier and the associated basket toward an inner ecliptic position, the compacted solids are acted upon by centrifugal force in a reverse direction so that they become loosened from the restraining wall (vane) and are flung from the basket radially over the edge of the associated basket and platform A further consideration arises in connection with the suncarth-moon relationship which is assumed by the vertical axis of the carrier 12, the baskets 116 which orbit about such axis, and the planetlike vanes 24 which orbit about the central axes of their respective baskets. When the nested vanes 24 of the baskets assume full outside ecliptic positions with respect to the axis of the carrier l2, these vanes oppose the slurry which is deposited in the central regions of the baskets and receive the slurry on the concave sides thereof under the influence of the centrifugal force which is imparted thereto by the rapidly rotating carrier. When the vanes assume inside ecliptic positions, they will be so disposed that the concave sides thereof face outwardly in the general radial direction of centrifugal movement so that any solid material adhering thereto after the compacted cake" of solids has been discharged will be flung therefrom and proceed diametrically across the basket where it will be caught by the particular vane which now assumes an outside ecliptic position, thus completely purging the first vane of adhering solid material. This purging or self-cleaning action is conducive toward continued trouble-free operation of the separator.

Considering the centrifugal separator in greater detail, the stationary framework thereof includes a base frame structure 40 (see FIG. ll) from which there projects upwardly an annular series of vertical supporting legs 42. Such legs carry a bearing cage 46 including a circular horizontal lower supporting plate 4-6, a circular horizontal upper supporting plate lit, and vertical connecting members 50 between the lower and upper plates. Vertically extending trapezoidal webs 52 which are secured to and project outwards from the bearing cage 4 4i serve to support at their upper ends a fixed horizontal annular platform 56 which supports thereon a plurality of circumferentially spaced inverted channel supports 56 having vertical side legs 57 which are supported on the platform 54 and horizontal connecting portions 58 each of which has bolted thereto a radially extending centering wing 59. The latter is provided with a domelike hood 60 which overlies the carrier deck plate H and its supported baskets 16. The apex region of the hood 66 serves to support a feed hopper 62 which constitutes an element of the aforementioned feed hopper and slurry distribution assembly 22.

The feed hopper 62 is mounted within an opening 64 which is formed centrally in the hood 66 rotatable is provided with a depending hollow stem portion 66. The latter projects downwardly within the central upper portion of the hood and communicates with the upper open end of a rotatable spiderlike distribution manifold 66 having downwardly and radially diverging branch conduits '70 which establish distribution channels 72 and discharge slurry into the central regions of the rotary baskets l6. As will be described in greater detail presently, the spiderlike distribution manifold 68 is driven in unison with the baskets 116, which is to say that the rate of rotation of the spiderlike slurry distribution manifold 68 is equal to the orbital speed of the baskets as they revolve about the vertical axis of the disclike carrier 12 so that proper feeding register of the distribution channels 72 with the baskets 116 is at all times maintained.

The vertically extending main drive shaft M for the rotary carrier 12 is of hollow or tubular construction and is rotatably supported in lower and upper bearing assemblies 76 and 76. The latter are of the taperlock type and thus assimilate the vertical thrust of the rotatable components which they serve. During operation of the separator, the vertically extending drive shaft M is continuously driven by an electric motor M which is suitably supported from the framework of the separator and to which it is connected in driven relationship by a belt and pulley arrangement 79. The latter embodies a small pulley on the lower end of the driven shaft of the motor M, a large pulley on the lower end of the main drive shaft 14, and an endless belt around the two pulleys. The upper end region of the drive shaft M is reduced and has mounted thereon and keyed thereto a vertically extending tubular drive sleeve 81, the lower end of the latter being formed with an outwardly extending annular flange 63 which serves to support thereon the rotatable deck plate type carrier 12. A drive hub 80 surrounds the drive sleeve 8i and has its lower end bolted to the flange. The carrier serves to support thereon a series of four bearing assemblies 82, there being one such bearing assembly for each of the baskets l6 and each bearing assembly serving rotatably to support one of the basket drive hubs 18. Each drive hub 18 at its upper end serves to support the associated horizontal basket platform 26.

As previously described, the various spiral vanes 24 of each basket 116 are supported along their lower edges on the associated disclike basket platform 26. A circular top all 84 is supported on the upper edges of the nested series of vanes 24 of each basket, and thus, it, in combination with the vanes and the basket platform, establishes a series of spiral passages between each pair of adjacent vanes. Each circular top wall 84 has a central opening 86 therethrough and the lower end of the associated branch conduit '70 of the rotatable spiderlike distribution manifold 63 projects through such opening so that the distribution channel 72 of the conduit may discharge slurry into the central region of the basket. Each top wall 84 has centrally mounted thereon an upper cup-shaped hub 88 which is rotatable in an upper bearing assembly 90, the latter being supported on an upper horizontal carrier plate 92 which is supported at the upper end of the tubular drive sleeve 80. The plate E 2 serves to support a series of arms 93 which are secured to the branch conduits '70 in supporting relationship.

in order effectively to lubricate the upper bearing assemblies )6 which are associated with the various baskets 16, oil mist is supplied through a conduit 96 tia swivel joint 96 from whence it passes upwardly through the: hollow drive shaft 14 and the sleeve 66. From the latter, the oil mist is distributed through radial branch passages 96 to the four upper bearing assemblies which, as previously pointed out, are associated with the baskets 116. The lower bearing: assemblies 82 for the baskets 16 may similarly be supplied with an oil mist through branch passages 99 which are only fragmentarily illustrated in the interests of clarity. The details of the distribution of oil mist from the sleeve 80 to the various bearing assemblies 82 and 90 are shown in FIG. 7 wherein it will be observed that the upper end of the sleeve 80 is closed by a plate 100 having fonned therein openings 102 which communicate through quick-release fittings 103 and elbow connections 104 with the various branch passages 98 and 99. Suitable T-fittings 105 (see FIG. 1) are interposed in the passages 98 and are connected to the passages 99.

As will be set forth in detail subsequently, means are provided for flushing the aforementioned discharge holes 34 which are formed in the basket platforms 26 and are associated with the hook portions 32 of the spiral vanes 24 at predetermined times during each rotation of each basket 16. Accordingly. a stationary vertically extending water supply pipe 110 (see FIGS. 1 and 7) projects downwardly through both the hopper 62 and the rotatable spiderlike distribution manifold 68, is supported at its upper end in the feed hopper 62 by a spider 111, and is connected through a swivel joint 112 with a series of four generally radially and outwardly extending water distribution branch pipes 114 which lead to the four baskets 16 respectively As will be made clear presently, when the nature of the individual baskets 16 has been further and more specifically described, the outer end of each water distribution branch pipe 114'communicates with a nonrotating outer bearing housing ring 116 (see particularly FlG. having an internal passage 118 leading to a slotlike pressure pocket 120 which periodically supplies momentary impulses of water under pressure to a series of three terminal carrier pipes 122 (see FIGS. 3, 4 and 5) by means of which such impulses are conducted to the hook portions 32 of the vanes 24 for flushing the holes 34 and conducting any accumulated solids to a region of discharge.

As shown in FIG. 6 of the drawings, the aforementioned radial branch passages 98 communicate through oil mist condensing fittings 124 with internal passages 126 which are formed in the outer bearing housing rings 116, such passages discharging the oil mist onto the upper sides of the upper bearing assemblies 90, each of which consists of an inner race 128 which is carried by the associated rotatable hub 88, an outer race 130 which is carried by the nonrotating outer bearing retaining ring 116, nd an annular series of bearing rollers 132 between the inner and outer races 128 and 130. An oil reservoir 134 is carried on each outer bearing retaining ring 116 and underlies the associated upper bearing assembly 90. Normally, when the separator is not in use, the oil reservoir is full, when carrier rotation commences, the oil establishes an annular pond" into which the bearing rollers 132 dip. This diplubrication augments the oil mist lubrication afforded by the oil passages 98.

The various nonrotating outer bearing housing rings 116 are maintained in a fixed position with respect to the carrier 12 by means of the horizontal plate 192 to which they are secured. The plate 92 thus prevents the outer bearing housing rings 116 from rotating, while at the same time, it causes said rings to follow the orbital path of the the baskets 16, thereby causing all of the radially disposed pipes 98 and 114 to swing about the vertical axis of the carrier and rotate the swivel joint.

The inner or inlet ends of the water carrier pipes 122 which are associated with each basket 16 are connected to elbow fittings 135 (see FIGS. 3, 4 and 5) which communicate with radial ports 136 in a porting ring 137 which is constrained to rotate with the top wall 84 of the basket 16 by means of a series ofdrive studs 138 (see H6. 6), such studs being carried in brackets 139 which are fixedly mounted on the top wall 84. The outer or outlet ends of the water carrier pipes 122 which are associated with each basket communicate through elbow fittings 141 with small holes 143 in the top wall 84 of the basket. These holes 143 register with the hook portions 32 of the spiral vanes 24. It will be apparent, therefore, that each time one of the radial ports 136 in the porting ring 137 moves into register with the water pocket 120 in the nonrotatable retaining ring 1 16, a quantity of water will be injected into the associated carrier pipe 122 and this water will be expelled from the outlet end of the pipe through the adjacent hole 143 in the top wall 84 of the basket so as to flush out the underlying hook portion 32 and its associated semisolids discharge outlet 34. The various carrier pipes 122 of each basket span approximately a are on the periphery of the basket so that each time one of the ports 136 moves into register with the water supply pocket at the 9 o'clock position wherein it is shown in FIG. 3, the flushing action will take place at the 6 oclock position which is 90 removed from the stationary pocket 120. From the above description, it will be apparent that the ports 136 and the pocket 120 constitute sliding cutoff valve devices by means of which the discharge holes 34 are periodically flushed.

Considering further the nature of an individual basket 16, and referring specifically to FIGS. 3 and 4, the basket platform 26 and the top wall 84 are maintained in their vertically spaced relationship by means of the various spiral vanes 24 which bear on edge against these circular basket parts or members. These vanes are of appreciable spiral or involute extent, and in the exemplary form of the invention, each vane encompasses approximately a 270 sector of the basket platform 26. At spaced regions along each vane 24, vertical openended tubes are welded to the convex side of the vane and receive therethrough clamping bolts 142 by means of which the adjacent top wall 86 and the adjacent platform 26 are caused to clamp the vane 24 therebetween. These tubes 140 and the bolts 142, in addition to maintaining the top wall 86, the platform 26 and the vanes 24 of each basket in their assembled relationship, also assimilate the outward radial thrust of the slurry undergoing treatment and prevent buckling, bulging or other deformation of the vanes. Suitable wear-resistant antifriction liners 144 and 146 may, if desired, be applied to the opposed surfaces of the top wall 84 and the platform 26 of each basket, such liners being formed of Teflon, Nylon or other material having the desired resistance to abrasion, as well as antifriction characteristics. As shown in FIG. 3, small deflector wings 148 extend between the tubes 140 and their associated vanes 24 in order to establish small ramp portions which deflect the slurry so that these tubes will offer no resistance to the free passage of the slurry along the vanes. Since the tubes travel generally in the liquid phase or region of the slurry, the deflector wings 148 prevent undue agitation of the liquid component of the slurry as it moves past the tubes 140.

The lower bearing assembly 82 of each basket 16, in addition to the aforementioned basket hub 18, includes a bearing unit proper 150 (see FIG. 1) having an inner race which is supported on the hub 18 and an outer race which is supported in a bearing cage 152. Such cage projects through and is supported on the rotatable carrier 12. The hub 18 of each basket, and consequently, the entire basket as a whole, is driven through a power train which derives its motion from the central vertical drive shaft 14 for the carrier 12 and which, as previously described, derives its motion from the motor M.

Considering now the power train for the baskets 16, such power train embodies a gear 154 (see FIG. 1) which is suitably fixedly secured to the vertical drive shaft 14 for the carrier 12 and meshes with a similar gear 156 on the lower end of a vertical jack shaft 158. The latter is journaled in bearing brackets 160 which are secured to one of the vertical connecting members 50. A second gear 162 on the upper end of the jack shaft meshes with a lower gear 164 which is mounted on the aforementioned floating drive sleeve 77. A sun gear 166 on the drive sleeve 77 meshes with idler planet gears 168 which are rotatably mounted on the lower ends of vertical spindle members 170 which are supported on the carrier 12. The idler planet gears 168 mesh with terminal power train gears 172 which are secured to downward extensions on basket hubs 18.

As previously stated, it is contemplated that a wide variety of rotational carrier speeds may be employed, depending, of course, on the character of the slurry which is undergoing treatment. Regardless of the particular carrier speed which is employed, rotational basket speed is only a very small fraction of the carrier speed and preferably is on the order of one-two hundredths of the carrier speed. Various speed ratios between carrier speed and basket speed may be attained by a process of gear substitution in the power train just described, but in any event, basket rotation must not be such that it affects the outward radial path which is imparted to the slurry when the latter is deposited on the baskets by reason of the centrifugal force arising form high speed rotation of the carrier. The outward radial path which is represented by the dotted line arrows C in FIG. a should at all times prevail so that the slurry will be flung against the concave sides of the various vanes 241 as they travel slowly and substantially endwise in the transverse direction with respect to the path tendency of the slurry.

It is to be noted at this point that in FIG. 1, the various gear diameters of the power train which includes the idler planet gears 16S and the sun gear 166 is such that with a 1,200 r.p.m. speed for the carrier 12, a speed ofjust above 1,000 r.p.m. is indicated for the individual baskets 2 1. This computation, however, does not take into consideration that the idler planet gears 16% are rolling about the periphery of the sun gear 166 so that it makes l,200 revolutions per minute. it gains, therefore, only one or two teeth displacements during each revolution and thus the basket speed is reduced to a speed which is of the order of6 r.p.m.

The manner in which separation of the three-phase variable density solids discharge materials is effected is disclosed in FIGS. 1 and 41. Three discharge areas, each of which is in he form of an annulus, are designated at L, SC, and S. L represents the clear liquid discharge annulus; SC represents the semiclear liquid discharge; and S represents the solids discharge.

The upper portion of the aforementioned basket drive power train, including the idler planet gears 168 and the gears 166 and 172 which mesh therewith are enclosed in a gear housing 176 in the form of a cup-shaped closure member which is supported by bolts 177 that are threadedly received in the carrier 12.

To separate the variable density solids, a first fixed cylindrical wall 190 surrounds the gear housing 176 and is supported on the webs 52. A second fixed wall 184 surrounds the wall 180, and in combination therewith, defines the discharge annulus for clear liquid. This second fixed wall 184, is provided with an inwardly projecting horizontal ledge portion 186 (see F1G.4) and is supported on he webs 52. A third fixed wall 188 is spaced outwardly from the wall 184 and likewise is supported from the webs 52. SAid third fixed wall is cylindrical and has at its upper end a horizontal shelf portion 190, the inner periphery of which directly opposes the peripheral rims of the basket platforms 26 and is at substantially the same horizontal level. Said wall 1138, in combination with the wall 184, defines the semiclear liquid discharge annulus SC.

A fourth cylindrical solids-deflection wall 192 is independently rotatable about the central vertical axis thereof. lt is belt driven under the control of an auxiliary motor M2 (see FIGS. 1 and 9), and in combination with the fixed wall 198, defines the solids discharge annulus S.

It has been set forth previously in connection with the description of HO. 8 how clear liquid flows downwardly through the small holes 30 which are disposed close to the convex sides of the various spiral vanes 2 1. it likewise has been explained how the semiclear liquid which becomes entrapped by the hook portions 32 of the vanes 241 flows downwardly through the holes 3 1. It has also been set forth how the solids which initially adhere to the vanes 24 in the form of a cake and bypass the hook portions are flung from the edge of the basket platforms 26 and thus leave the baskets. Considering now these three different categories of separated materials, the clear liquid which issues from the holes 311 passes downwardly through relatively long depending discharge tubes 1941 (see F108. 1 and 1) which extend below the level of the aforementioned horizontal ledge portion 186 so that the liquid is conducted beneath this ledge portion and flows downwardly through the discharge annulus L from whence it may be collected for conduction away from the separator. The semiclear liquid which passes downwardly through the holes 3 1 passes through relatively short depending tubes 196 which terminate in a plane slightly above the level of the horizontal ledge portion 1% so that this material flows downwardly through the discharge annulus SC for separate conduction from the separator. The nearly dry solids which are flung from the periphery of the baskets pass over and across the horizontal shelf portion of the wall 188 and are flung against the rotating wall 192 from whence they fall downwardly by gravity through the annulus S and also are separately conducted from the separator.

in order to remove such solids as accumulate on the wall 192, fixed scraper elements 2011 are secured by bolts 202 (see F 16. 2) to the cylindrical wall 188 and bear against the rotating wall 192, the loosened solids falling through the discharge annulus S. The cylindrical wall 192 is adapted to be driven at a relatively low rate of speed by the aforementioned auxiliary motor M2. the latter operating through a gear reduction device 204 having an output shaft 206. Said shaft carries a drive pulley ans over which a dual drive belt 210 passes. The belt also passes around a drum 212 which is secured to and encircles the cylindrical wall 192. A spring-biased tension takeup roller 21a maintains the necessary tension in the belt for drive purposes.

The rotating cylindrical wall 192 and its associated drum 212 are rotatably supported by peripherally disposed pairs of rollers including horizontal rollers 220 (see FIGS. 1 and 2) and vertical rollers 222. The rollers .220 are rotatably supported in U-shaped supports 224 which are secured to the annular platform 541, the rollers and their supports being disposed within the confines of the inverted channel supports 56. The rollers 222 are rotatably supported in supports 228 which depend from the platform 54. Cover plates 230 serve to close the outer open sides of the inverted channel supports 56 and may be removed to afford access to the rollers 220 when desired. Said rollers 220 are centering rollers for the rotating wall 192 and its associated drum 210, while the rollers 222 are supporting traction rollers therefor. A cylindrical wall 231 which is supported on the platform 54 constitutes a guard for the drive belt 210. An additional upstanding cylindrical wall 233 projects upwardly from the platform 54 between the rotating wall 192 and its associated drum 212 and constitutes a shield for preventing solids from reaching the rollers 222.

In the operation of the herein described centrifugal separator, the slurry or other material to be separated is supplied to the feed hopper 62 from whence it flows downwardly to provide a divided flow through the various distribution channels 72 for discharge into the baskets 16 in the central regions thereof. Since the distribution channels rotate in timed relation to the orbital speed of the baskets about the axis of the carrier 12, the slurry will be deposited continuously in the central regions of the baskets and one the basket platforms 26 substantially in the center of the nested arrangements of three spiral vanes. it will be recalled that the rate of rotation of the baskets is relatively slow so that such rotational movements thereof impart little or no centrifugal potential to the slurry that is deposited therein. However, since the rate of rotation of the carrier is relatively great, as soon as the slurry is deposited on the platforms 26, a high centrifugal force is imparted thereto tending to fling the same outwardly of the carrier 12 and radially across the horizontal surfaces of the slowly rotating platforms away from the axis of the carrier. Due to the overlapping arrangement between the trailing region of each involute vane 24 and the leading region of the next adjacent vane, some portion at least of one of the vanes will be disposed in the path of movement of the slurry on each baseplate, and thus, slurry will be forcibly projected against the concave side of such one vane.

Applying the theory of relativity to the centrifugal phenomena which presents itself in this case, each vane thus functions somewhat in the manner of a tilting receptacle containing a mixture of solids and liquid. The centrifugal force acting on the mixture is many times the force of gravity and it throws the solids radially against the bottom" of the receptacle which, in this instance, is the concave side of the vane. The majority of the solids becomes compacted on the bottom" of the receptacle (vane) in the form of a cake. Other solids which does not have the necessary time to settle, remains in suspension and collects near the bottom of the receptacle in the vicinity of the cake, while substantially clear liquid remains near the top" of the receptacle, i.e., in the vicinity of the small holes 30. The net result is that a diminishing solidsgradation takes place and the clear liquid is drained off through the holes 30 and their associated relatively long discharge tubes 194 and thus flows out through the discharge annulus L as previously described. At the same time, additional liquid and some solids which have not been compacted are trapped by the hook portions 32 on the vanes 24 and flows out in the form of a semiclear liquid through the holes 34, the short discharge tubes 196, and the annulus SS. Removal of liquid by way of the holes 30, and of additional liquid with some solids by way of the holes 34, proceeds at a rate somewhat faster than the rate of feed of slurry into the baskets so that by the time the trailing or outer edge of any given vane has closely approached the periphery of the carrier 12, the receptacle" (vane) has been drained of its liquid content and only the compacted cake of solids remains on the concave side of the vane. The subsequent direction change of the vane as it moves inwardly with respect to the carrier results in a reversal of the centrifugal force which is applied to the caked solids with the result that the latter become loosened and restored to the free gravitational field where they are flung radially outwardly and against the rotating wall 192 from whence they are discharged downwardly through the annulus S.

Clogging of the various holes 34 is avoided by the previously described flushing action which is intermittently exerted upon such holes once during each 360 movement thereof around the rotational axes of the baskets, or in other words, at intervals of approximately every seconds on the basis of a basket which rotates at 6 rpm. At the risk of repetition, this flushing action is initiated each time one of the three ports 136 in the rotating porting ring (see H08. 3, 4 and 5) moves into radial register with the water under pressure in the fixed pocket 120 so that a momentary supply of water is conducted through the adjacent carrier pipe 122 and introduced through the small hole 143 in the top wall 84 of each basket at a region of 90 removed from the pocket, such hole being in vertical register with one of the hook portions 32 of one of the vanes 24 at the precise moment that the port 136 moves into register with the fixed pocket 120. Such water impulse not only flushes the adjacent discharge hole 34 but it also flushes the hook portion 32 of the vane 24.

From the above description, it is believed that the nature and many advantages of the herein described centrifugal separator will be understood without further description. The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. I

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

l. A centrifugal separator adapted to dehydrate solids in a slurry and comprising a horizontal carrier which is rotatable about a central vertical axis, a plurality of separator baskets eccentrically and rotatably mounted on said carrier in circumferentially spaced relationship for rotation about respective vertical axes and for orbital movement about the axis of the carrier, each basket including a horizontal basket platform adapted to receive slurry thereon, distribution channels rotatable with the carrier and leading to the central regions of the basketsfor depositing slurry therein, each basket further including a plurality of imperforate slurry-restraining walls projecting upwardly from said platform and presenting concave surfaces which face generally inwardly of the platform so that each time an individual wall assumes an outside ecliptic position with respect to the axis of the carrier and the axis of the bwket, slurry will be flung radially outwardly of the carrier by centrifugal force and the solids therein caused to settle toward and against the concave surface of such wall while a diminishing solids graduation will take place radially inwardly of both the basket and the carrier, and when such wall progresses toward an inside ecliptic position, the settled solids on the concave wall surface will be dislodged by centrifugal force and flung from the basket, there being a series of first openings in said platform between said concave surface and the axis of the basket at a region of sparse solids density radially remote from aid concave surface for discharge of substantially solids-free clear liquid from the basket, and a second discharge opening between said concave surface and the axis of the basket at a region of high solids density close to said concave surface for discharge of semiclear liquid from the basket, means underlying the carrier, common to all of the baskets, and establishing a first discharge annulus for the liquid issuing from said series of first openings in the basket platforms, means underlying the carrier, common to all of the baskets, and establishing a second discharge annulus for the semiclear liquid issuing from said second openings in the basket platforms, means establishing a third discharge annulus for solids which are flung from the baskets, means for rotating the carrier at a relatively high rate of speed, means for rotating the individual baskets at such slow rate of speed that no appreciable centrifugal force is imparted to the slurry deposited thereon other than that which is imparted thereto by rotation of the carrier.

2. A centrifugal separator as set forth in claim 1 and wherein the concave surfaces of said walls are generally of involute configuration, have their leading edges disposed in the vicinity of the axis of rotation of the basket and their trailing edges positioned adjacent the periphery of the basket, and are disposed in circumferentially spaced, intertwined, nested, circumferentially and radially overlapping relationship.

3. A centrifugal separator as set forth in claim 2 and wherein each concave wall surface encompasses a major sector of the associated basket platform.

4. A centrifugal separator as set forth in claim 3 and wherein each concave wall is established by the provision of an upstanding involute vane which encompasses approximately a 270 sector of the associated basket platform.

5. A centrifugal separator as set forth in claim 4 and including, additionally, means in the vicinity of said second opening for entrapping said semiclear liquid and directing it toward said latter opening.

6. A centrifugal separator as set forth in claim 5 and wherein said second opening is disposed in close proximity to the trailing edge of the vane and said entrapping and directing means for the semiclear liquid comprises a hooklike reentrant portion which is formed on the trailing edge of the vane and partially encompasses said second opening.

7. A centrifugal separator as set forth in claim 6 and including, additionally, a top wall for each basket overlying the vanes thereof, said top wall, in combination with the basket platform and each pair of adjacent vanes, establishing an involute guide path for slurry during rotation of the basket and through which the slurry passes during settling of the solids therein under the centrifugal force imparted thereto due to the high speed rotation of the carrier.

8. A centrifugal separator as set forth in claim 7 and including, additionally, opposed antifriction liners disposed on and coextensive with said basket platform and top wall.

9. A centrifugal separator as set forth in claim 7 and including, additionally, a series of vane-reinforcing tubes extending vertically between said basket platform and top wall, and clamping bolts projecting through said tubes and serving to clamp said top wall against the upper edges of the vanes.

10. A centrifugal separator as set forth in claim 9 and including, additionally, a series of deflector wings extending between the vanes and vane-reinforcing tubes and establishing ramp portions which deflect the slurry past said tubes.

11. A centrifugal separator as set forth in claim 6 and including additionally, means incident to and effective during rotation of each basket for periodically injecting a supply of fresh water against each reentrant hook portion to flush residual solids through said second opening in the basket platform.

112. A centrifugal separator as set forth in claim 6 and including, additionally, a nonrotating retaining ring for each basket,.encompassing a portion of the latter, fixed to and movable bodily with the carrier, and provided with a water distributing pressure pocket therein, a porting ring concentric with the basket and rotatable bodily therewith, a plurality of water-distributing channels mounted on and movable bodily with the basket and having outlet ends disposed in flushing register with the hook portions of the vanes, said channels having their inlet ends secured to said porting ring, and sliding cutoff valve means on the porting ring and retaining ring and effective during rotation of the baskets to intermittently admit predetermined quantities of water from the pressure pocket to the channels for conduction to said hook portions, and means for continuously supplying water under pressure to said pressure pocket.

13. A centrifugal separator as set forth in claim 12 and wherein said sliding cutoff valve means comprises a series of radial bores in the porting ring and in communication with the inlet ends of said distributing channels and movable into and out of register with said pressure pockets during rotation of the basket.

M. A centrifugal separator as set forth in claim 11 and including, additionally, a roller bearing assembly interposed between said nonrotating retaining ring and the basket, said retaining ring being provided with internal oil passages leading to said roller bearing, and means for continuously supplying oil to said internal oil passages.

15, A centrifugal separator as set forth in claim it and wherein said means for rotating said carrier at high speed comprises a central vertical drive shaft upon which the carrier is mounted in coaxial relationship and the means for rotating the basket at slow speed comprises a first gear mounted on said drive shaft, a rotatable basket drive sleeve disposed on said drive shaft, a jack shaft mounted for rotation about a fixed vertical axis, a second gear on said drive sleeve, third and fourth gears mounted on the jack shaft and meshing with said first and second gears respectively, and a system of planetary gearing connecting said second gear to the basket in driving relationship, said planetary gearing comprising a sun gear mounted on aid drive sleeve, a terminal gear mounted on the basket, and a planet idler gear meshing with said sun gear and terminal gear and mounted on the carrier.

16. A centrifugal separator as set forth in claim 1 and including, additionally, a cylindrical solids deflection wall concentric with the carrier and disposed at the general horizontal level of the basket platforms for directing slurry flung from the baskets into said third annulus.

l7. A centrifugal separator as set forth in claim it: and wherein said solids-deflection wall is rotatable about the axis of the carrier, and the separator further includes a series of fixed scraper blades which makes sliding contact with said solids-deflection wall for dislodging solids which adhere to the latter and causing them to be discharged into said third discharge annulus, and means for rotating said solids-deflection wall.

18. A centrifugal separator as set forth in claim 37 and wherein he means for rotating said solids-deflection wall is separate from the means for rotating the carrier and comprises an electric motor having a drive pulley thereon, and an endless flexible drive member encompassing said solids-deflection wall and drive pulley.

19. A centrifugal separator adapted to dehydrate solids in a slurry and comprising a stationary framework, a vertical drive shaft rotatably mounted on said framework, a carrier in the form of a horizontal circular deck plate secured to said drive shaft for rotation in a horizontal plane, a plurality of separator baskets eccentrically mounted on said deck plate for rotation about respective vertical axes and for orbital movement around said drive shaft, each basket including a horizontal basket platform adapted to receive slurry thereon and disposed a slight distance above the plane of said deck plate, each basket further including a plurality of imperforate nested, involute, spiral circumferentially spaced and circumferentially and radially overlapping vanes which project upwardly from said platform and presenting concave slurryrestraining surfaces which face generally inwardly of the platform so that each time an individual vane assumes an outside ecliptic position with respect to the axis of the carrier and the axis of the basket, slurry will be flung radially outwardly of the carrier by centrifugal force and the solids therein caused to settle with a diminishing solids gradation inwardly of the carrier against said concave surface, and when said vane progresses toward an inside ecliptic position, the settled solids on said concave surface will be dislodged by centrifugal force and flung from the periphery of the platform, there being a first discharge opening in said platform at a region of sparse solidsdensity, and a second discharge opening in said platform at a region of higher solids density, and a plurality of concentric annular walls mounted on the framework and including first and second fixed walls which define therebetween a first discharge annulus for the material issuing from the first discharge openings in said basket platforms, a third fixed wall which, in combination with said second wall, defines a second discharge annulus for the material issuing from the second discharge openings in said basket platforms, and a fourth rotatable wall which, in combination with said third wall, defines a third discharge annulus for material issuing from the edges of said basket platforms, at fixed scraper element mounted on said framework and cooperating with said rotatable wall for removing material deposited on said latter wall and causing the same to fall by gravity into said third annulus, and means for rotating said fourth wall.

20. A centrifugal separator as set forth in claim 19 and wherein said second fixed annular wall is provided with an inturned horizontal ledge portion which extends between said basket platform and the deck plate, said first discharge opening communicates with a relatively long discharge tube which extends below the level of said ledge portion for discharging the sparse density material into said first annulus beneath said ledge portion, and said second discharge opening communicates with a relatively short discharge tube which lies wholly above the level of said ledge portion for discharging the higher density material into said second annulus above said ledge.

M. A centrifugal separator as set forth in claim 20 and including, additionally, a series of wall-confining rollers rotatably carried by the framework and tractionally engaging the outer side of said rotatable wall for centering the same with respect to said drive shaft, and a second series of rollers rotatably carried by the framework and tractionally engaging said rotatable wall in wall-supporting relationship.

22. A centrifugal separator as set forth in claim 19 and wherein said vertical drive shaft is of hollow tubular construction, each basket is supported on the deck plate by means of roller bearings, which are surrounded by nonrotatable housing rings having oil passages therein leading to the bearings, the upper end of the tubular drive shaft communicates through a series of radially extending oil distribution pipes with said passages in the retaining rings, and the lower end of said tubular drive shaft communicates through a swivel joint with a source of oil under pressure.

23. A centrifugal separator as set forth in claim 19 and wherein said nonrotatable retaining rings are provided with water-distributing pressure pockets therein, a porting ring surrounds each nonrotating retaining ring, is connected to the associated basket platform for rotation in unison therewith, and is provided with radial ports therein which communicate through water-distributing channels having outlet ends in the vicinity of said second discharge openings in the basket platforms whereby, upon register of the radial ports with the pressure pockets, quantities of water under pressure are con ducted through the water-distributing channels to said second discharge opening for flushing purposes, a second swivel joint is supported on the upper end of said drive shaft, is connected to a source of water under pressure, and is connected through a series of radially extending water distributing pipes to said pressure pockets.

24. A centrifugal separator adapted to dehydrate solids in a slurry and comprising a stationary framework, a vertical hollow tubular drive shaft rotatably mounted on the framework, a carrier having a horizontal de'ck plate secured to the drive shaft for rotation in its horizontal plane, a plurality of separator baskets including horizontal basket platforms adapted to receive slurry centrally thereon and upper and lower hubs mounted on the carrier for rotation about respective vertical axes and for orbital movement about said drive shaft, a plurality of separator vanes eccentrically mounted on the basket platforms in circumferentially spaced relationship and movable, upon rotation of the basket, through inside and outside ecliptic positions and against which slurry is directed by centrifugal force when the vanes are in their outside ecliptic positions for separation of the solids at inner regions of sparse solids'density and outer regions of heavy solids-density,

discharge openings in said platforms at said inner and outer regions of solids-density, roller bearings for rotatably supporting said upper and lower hubs, restraining rings mounted on the carrier and encompassing said roller bearings, there being oil passages in said restraining rings leading to the bearings, radially extending oil distribution channels in communication with the upper region of said drive shaft and with said oil passages in the restraining rings, there being water passages in said restraining rings, porting rings surrounding said restraining rings, water-distributing channels mounted on and movable bodily with the basket and having outlet ends in flushing register with the discharge openings in the platforms at the regions of heavy solids-density, and having their inner ends secured to the porting rings, sliding cutofi' valve means on the porting rings and retaining rings and effective during rotation of the baskets to intermittently admit predetermined quantities of water from the water passages to the water-distributing channels for conduction to said latter discharge openings, a fixed water supply pipe coaxial with said drive shaft, a swivel joint in communication with said water supply pipe, water distributing channels leading from said swivel joint to said water passages in the retaining rings, a swivel joint in communication with said hollow tubular drive shaft, and a fixed oil supply pipe in communication with said latter swivel joint.

I! I! t t l 

1. A centrifugal separator adapted to dehydrate solids in a slurry and comprising a horizontal carrier which is rotatable about a central vertical axis, a plurality of separator baskets eccentrically and rotatably mounted on said carrier in circumferentially spaced relationship for rotation about respective vertical axes and for orbital movement about the axis of the carrier, each basket including a horizontal basket platform adapted to receive slurry thereon, distribution channels rotatable with the carrier and leading to the central regions of the baskets for depositing slurry therein, each basket further including a plurality of imperforate slurry-restraining walls projecting upwardly from said platform and presenting concave surfaces which face generally inwardly of the platform so that each time an individual wall assumes an outside ecliptic position with respect to the axis of the carrier and the axis of the basket, slurry will be flung radially outwardly of the carrier by centrifugal force and the solids therein caused to settle toward and against the concave surface of such wall while a diminishing solids graduation will take place radially inwardly of both the basket and the carrier, and when such wall progresses toward an inside ecliptic position, the settled solids on the concave wall surface will be dislodged by centrifugal force and flung from the basket, there being a series of first openings in said platform between said concave surface and the axis of the basket at a region of sparse solids density radially remote from aid concave surface for discharge of substantially solids-free clear liquid from the basket, and a second discharge opening between said concave surface and the axis of the basket at a region of high solids density close to said concave surface for discharge of semiclear liquid from the basket, means underlying the carrier, common to all of the baskets, and establishing a first discharge annulus for the liquid issuing from said series of first openings in the basket platforms, means underlying the carrier, common to all of the baskets, and establishing a second discharge annulus for the semiclear liquid issuing from said second openings in the basket platforms, means establishing a third discharge annulus for solids which are flung from the baskets, means for rotating the carrier at a relatively high rate of speed, means for rotating the individual baskets at such slow rate of speed that no appreciable centrifugal force is imparted to the slurry deposited thereon other than that which is imparted thereto by rotation of the carrier.
 2. A centrifugal separator as set forth in claim 1 and wherein The concave surfaces of said walls are generally of involute configuration, have their leading edges disposed in the vicinity of the axis of rotation of the basket and their trailing edges positioned adjacent the periphery of the basket, and are disposed in circumferentially spaced, intertwined, nested, circumferentially and radially overlapping relationship.
 3. A centrifugal separator as set forth in claim 2 and wherein each concave wall surface encompasses a major sector of the associated basket platform.
 4. A centrifugal separator as set forth in claim 3 and wherein each concave wall is established by the provision of an upstanding involute vane which encompasses approximately a 270* sector of the associated basket platform.
 5. A centrifugal separator as set forth in claim 4 and including, additionally, means in the vicinity of said second opening for entrapping said semiclear liquid and directing it toward said latter opening.
 6. A centrifugal separator as set forth in claim 5 and wherein said second opening is disposed in close proximity to the trailing edge of the vane and said entrapping and directing means for the semiclear liquid comprises a hooklike reentrant portion which is formed on the trailing edge of the vane and partially encompasses said second opening.
 7. A centrifugal separator as set forth in claim 6 and including, additionally, a top wall for each basket overlying the vanes thereof, said top wall, in combination with the basket platform and each pair of adjacent vanes, establishing an involute guide path for slurry during rotation of the basket and through which the slurry passes during settling of the solids therein under the centrifugal force imparted thereto due to the high speed rotation of the carrier.
 8. A centrifugal separator as set forth in claim 7 and including, additionally, opposed antifriction liners disposed on and coextensive with said basket platform and top wall.
 9. A centrifugal separator as set forth in claim 7 and including, additionally, a series of vane-reinforcing tubes extending vertically between said basket platform and top wall, and clamping bolts projecting through said tubes and serving to clamp said top wall against the upper edges of the vanes.
 10. A centrifugal separator as set forth in claim 9 and including, additionally, a series of deflector wings extending between the vanes and vane-reinforcing tubes and establishing ramp portions which deflect the slurry past said tubes.
 11. A centrifugal separator as set forth in claim 6 and including additionally, means incident to and effective during rotation of each basket for periodically injecting a supply of fresh water against each reentrant hook portion to flush residual solids through said second opening in the basket platform.
 12. A centrifugal separator as set forth in claim 6 and including, additionally, a nonrotating retaining ring for each basket, encompassing a portion of the latter, fixed to and movable bodily with the carrier, and provided with a water distributing pressure pocket therein, a porting ring concentric with the basket and rotatable bodily therewith, a plurality of water-distributing channels mounted on and movable bodily with the basket and having outlet ends disposed in flushing register with the hook portions of the vanes, said channels having their inlet ends secured to said porting ring, and sliding cutoff valve means on the porting ring and retaining ring and effective during rotation of the baskets to intermittently admit predetermined quantities of water from the pressure pocket to the channels for conduction to said hook portions, and means for continuously supplying water under pressure to said pressure pocket.
 13. A centrifugal separator as set forth in claim 12 and wherein said sliding cutoff valve means comprises a series of radial bores in the porting ring and in communication with the inlet ends of said distributing channels and movable into and out of register with said pressure pockets during Rotation of the basket.
 14. A centrifugal separator as set forth in claim 1 and including, additionally, a roller bearing assembly interposed between said nonrotating retaining ring and the basket, said retaining ring being provided with internal oil passages leading to said roller bearing, and means for continuously supplying oil to said internal oil passages.
 15. A centrifugal separator as set forth in claim 1 and wherein said means for rotating said carrier at high speed comprises a central vertical drive shaft upon which the carrier is mounted in coaxial relationship and the means for rotating the basket at slow speed comprises a first gear mounted on said drive shaft, a rotatable basket drive sleeve disposed on said drive shaft, a jack shaft mounted for rotation about a fixed vertical axis, a second gear on said drive sleeve, third and fourth gears mounted on the jack shaft and meshing with said first and second gears respectively, and a system of planetary gearing connecting said second gear to the basket in driving relationship, said planetary gearing comprising a sun gear mounted on said drive sleeve, a terminal gear mounted on the basket, and a planet idler gear meshing with said sun gear and terminal gear and mounted on the carrier.
 16. A centrifugal separator as set forth in claim 1 and including, additionally, a cylindrical solids deflection wall concentric with the carrier and disposed at the general horizontal level of the basket platforms for directing slurry flung from the baskets into said third annulus.
 17. A centrifugal separator as set forth in claim 16 and wherein said solids-deflection wall is rotatable about the axis of the carrier, and the separator further includes a series of fixed scraper blades which makes sliding contact with said solids-deflection wall for dislodging solids which adhere to the latter and causing them to be discharged into said third discharge annulus, and means for rotating said solids-deflection wall.
 18. A centrifugal separator as set forth in claim 17 and wherein the means for rotating said solids-deflection wall is separate from the means for rotating the carrier and comprises an electric motor having a drive pulley thereon, and an endless flexible drive member encompassing said solids-deflection wall and drive pulley.
 19. A centrifugal separator adapted to dehydrate solids in a slurry and comprising a stationary framework, a vertical drive shaft rotatably mounted on said framework, a carrier in the form of a horizontal circular deck plate secured to said drive shaft for rotation in a horizontal plane, a plurality of separator baskets eccentrically mounted on said deck plate for rotation about respective vertical axes and for orbital movement around said drive shaft, each basket including a horizontal basket platform adapted to receive slurry thereon and disposed a slight distance above the plane of said deck plate, each basket further including a plurality of imperforate nested, involute, spiral circumferentially spaced and circumferentially and radially overlapping vanes which project upwardly from said platform and presenting concave slurry-restraining surfaces which face generally inwardly of the platform so that each time an individual vane assumes an outside ecliptic position with respect to the axis of the carrier and the axis of the basket, slurry will be flung radially outwardly of the carrier by centrifugal force and the solids therein caused to settle with a diminishing solids gradation inwardly of the carrier against said concave surface, and when said vane progresses toward an inside ecliptic position, the settled solids on said concave surface will be dislodged by centrifugal force and flung from the periphery of the platform, there being a first discharge opening in said platform at a region of sparse solids-density, and a second discharge opening in said platform at a region of higher solids density, and a plurality of concentric annular walls mounted on the framework and including fiRst and second fixed walls which define therebetween a first discharge annulus for the material issuing from the first discharge openings in said basket platforms, a third fixed wall which, in combination with said second wall, defines a second discharge annulus for the material issuing from the second discharge openings in said basket platforms, and a fourth rotatable wall which, in combination with said third wall, defines a third discharge annulus for material issuing from the edges of said basket platforms, a fixed scraper element mounted on said framework and cooperating with said rotatable wall for removing material deposited on said latter wall and causing the same to fall by gravity into said third annulus, and means for rotating said fourth wall.
 20. A centrifugal separator as set forth in claim 19 and wherein said second fixed annular wall is provided with an inturned horizontal ledge portion which extends between said basket platform and the deck plate, said first discharge opening communicates with a relatively long discharge tube which extends below the level of said ledge portion for discharging the sparse density material into said first annulus beneath said ledge portion, and said second discharge opening communicates with a relatively short discharge tube which lies wholly above the level of said ledge portion for discharging the higher density material into said second annulus above said ledge.
 21. A centrifugal separator as set forth in claim 20 and including, additionally, a series of wall-confining rollers rotatably carried by the framework and tractionally engaging the outer side of said rotatable wall for centering the same with respect to said drive shaft, and a second series of rollers rotatably carried by the framework and tractionally engaging said rotatable wall in wall-supporting relationship.
 22. A centrifugal separator as set forth in claim 19 and wherein said vertical drive shaft is of hollow tubular construction, each basket is supported on the deck plate by means of roller bearings, which are surrounded by nonrotatable housing rings having oil passages therein leading to the bearings, the upper end of the tubular drive shaft communicates through a series of radially extending oil distribution pipes with said passages in the retaining rings, and the lower end of said tubular drive shaft communicates through a swivel joint with a source of oil under pressure.
 23. A centrifugal separator as set forth in claim 19 and wherein said nonrotatable retaining rings are provided with water-distributing pressure pockets therein, a porting ring surrounds each nonrotating retaining ring, is connected to the associated basket platform for rotation in unison therewith, and is provided with radial ports therein which communicate through water-distributing channels having outlet ends in the vicinity of said second discharge openings in the basket platforms whereby, upon register of the radial ports with the pressure pockets, quantities of water under pressure are conducted through the water-distributing channels to said second discharge opening for flushing purposes, a second swivel joint is supported on the upper end of said drive shaft, is connected to a source of water under pressure, and is connected through a series of radially extending water distributing pipes to said pressure pockets.
 24. A centrifugal separator adapted to dehydrate solids in a slurry and comprising a stationary framework, a vertical hollow tubular drive shaft rotatably mounted on the framework, a carrier having a horizontal deck plate secured to the drive shaft for rotation in its horizontal plane, a plurality of separator baskets including horizontal basket platforms adapted to receive slurry centrally thereon and upper and lower hubs mounted on the carrier for rotation about respective vertical axes and for orbital movement about said drive shaft, a plurality of separator vanes eccentrically mounted on the basket platforms in circumferentially spaced relationship and movable, upon rotation of the basket, through inside and outside ecliptic positions and against which slurry is directed by centrifugal force when the vanes are in their outside ecliptic positions for separation of the solids at inner regions of sparse solids-density and outer regions of heavy solids-density, discharge openings in said platforms at said inner and outer regions of solids-density, roller bearings for rotatably supporting said upper and lower hubs, restraining rings mounted on the carrier and encompassing said roller bearings, there being oil passages in said restraining rings leading to the bearings, radially extending oil distribution channels in communication with the upper region of said drive shaft and with said oil passages in the restraining rings, there being water passages in said restraining rings, porting rings surrounding said restraining rings, water-distributing channels mounted on and movable bodily with the basket and having outlet ends in flushing register with the discharge openings in the platforms at the regions of heavy solids-density, and having their inner ends secured to the porting rings, sliding cutoff valve means on the porting rings and retaining rings and effective during rotation of the baskets to intermittently admit predetermined quantities of water from the water passages to the water-distributing channels for conduction to said latter discharge openings, a fixed water supply pipe coaxial with said drive shaft, a swivel joint in communication with said water supply pipe, water distributing channels leading from said swivel joint to said water passages in the retaining rings, a swivel joint in communication with said hollow tubular drive shaft, and a fixed oil supply pipe in communication with said latter swivel joint. 